Technical Support Document 

 for 

EPA's Proposed Rulemaking 

on revisions to the 

California State Implementation Plan 

as submitted by the State of California, Air Resources Board 

for the Imperial County Air Pollution Control District 

 

EPA's Analysis of 

Imperial County Air Pollution Control District’s 

Rule 420- Beef Feedlots 

United States Environmental Protection Agency, Region IX 

 Air Division 

 

January 2010 
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Imperial County Air Pollution Control District (ICAPCD), 

Rule 420 - Beef Feedlots 

Chronology of ICAPCD Adoption, Air Resources Board Submittal, and EPA Actions 

- The ICAPCD Governing Board adopted Rule 420 on October 10, 2006. 

- The State of California submitted Rule 420 to EPA on August 24, 2007 as a revision to the California 

State Implementation Plan (SIP). 

- On September 17, 2007, EPA found complete California Air Resource Board’s (CARB) submittal of 

Rule 420. 

EPA incorporated a prior version of Rule 420 into the SIP. Please see 68 Federal Register (FR) 8839, 

February 26, 2003. 

Rule Summary

ICAPCD Rule 420 - Beef Feedlots, is designed to limit the emission of particulate matter from beef 

feedlots using a Dust Control Plan based on: (1) maintaining at target minimum and maximum soil 

moisture content; and, (2) manure management practices designed to prevent adverse public health 

conditions. 

Statutory Requirements & EPA Guidance

In Section 189 of the Clean Air Act Amendments of 1990 (CAA), Congress required that serious PM 

nonattainment areas implement in a stepwise manner all reasonably available control measures (RACM) 

rules, then all best available control measures (BACM) for PM. On August 11, 2004, Imperial County 

was reclassified as a serious PM nonattainment area (see 69 FR 48792). Subsequently, on December 11, 

2007, EPA found that Imperial County failed to meet the serious area attainment deadline of December 

31, 2001 and must now submit a “5% Plan” pursuant to Section 189(d) of the CAA (see 72 FR 70222). 

This “5% Plan” was due December 11, 2008. The Imperial County Board adopted a PM-10 Plan in 

August 2009 and forwarded it to CARB for submittal to us. CARB has not submitted the plan. 

 

ICAPCD produced two analyses to define the significant sources of PM-10 contributing to violations of 

the PM-10 standard: (1) “Draft Final Technical Memorandum Regulation VIII BACM Analysis,” 

October 2005; and, (2) an updated BACM analysis in “2009 Imperial County State Implementation Plan 

for Particulate Matter Less Than 10 Microns in Aerodynamic Diameter,” August 11, 2009. In these 

analyses, ICAPCD showed that PM-10 emissions from beef feedlots were below the de minimus 

threshold for requiring BACM and are not significant sources of PM-10. Please see the table below. 

 

Imperial County 
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Beef Feedlot and Dairy Cattle PM10 Emissions 

(tons per day) 

2004 

(1) 

2004 

(2) 

2005 

(3) 

2006 

(3) 

Uncontrolled emissions 5.22 4.66 5.52 6.52 

Rule 420 controlled emissions 

(50% emission reduction credited 2002) 

2.62 2.33 2.76 3.26 

Significant source or “de minimis” threshold 4.9 4.9 5.62 5.64 

(1) Source, “Draft Final Technical Memorandum Regulation VIII BACM Analysis” October 2005, page 15. 

(2) Source, “2009 Imperial County State Implementation Plan for Particulate Matter Less Than 10 Microns in 

Aerodynamic Diameter,” August 11, 2009 (using October 2005 calculated de minimis level) 

(3) Source, “2009 Imperial County State Implementation Plan for Particulate Matter Less Than 10 Microns in 

Aerodynamic Diameter,” August 11, 2009, Appendix III, page III-2. 

Consequently, we are not evaluating Rule 420 as a BACM rule; instead, we will evaluate this rule for its 

enforceability and whether it maintains or strengthens the Imperial County SIP. 

Please see 59 FR 41998 for a discussion of how we calculate the “de minimis” or significant source 

threshold for requiring BACM on significant sources. 

1. Enforceability and Legal Sufficiency Requirements (CAA §§ 110(a)(2), 172(c)(6)) 

Section 110(a)(2)(A) of the CAA states that implementation plans must include “enforceable emission 

limitations and other control measures, means, or techniques... as may be necessary or appropriate to 

meet the applicable requirements of [the CAA].” CAA § 110(a)(2)(A); see also CAA § 172(c)(6), 

General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990, 57 Fed. 

Reg. 13498 (April 16, 1992). Accordingly, regulations submitted to EPA for approval into a SIP must 

be legally enforceable. 

2. Anti-Backsliding Requirements and Findings (CAA § 110(l)) and (CAA § 193). 

Section 110(l) of the CAA states that “[t]he Administrator shall not approve a revision of a plan if the 

revision would interfere with any applicable requirement concerning attainment and reasonable further 

progress (as defined in [CAA § 171]), or any other applicable requirement of this chapter.” For 

example, EPA cannot approve a rescission, delayed implementation of a SIP-approved rule, or adoption 

of emission limits less stringent than the SIP-approved rule that would interfere with reasonable further 

progress (RFP) toward or attainment of the NAAQS. EPA must review this submitted version of Rule 

420 and compare it with the earlier February 2003 SIP-approved regulation. EPA must find that 

Rule 420, adopted October 10, 2006, is consistent with Section 110(l) of the CAA. 

Section 193 of the Act (the “Savings Clause”) states that “[n]o control requirement in effect, or required 

to be adopted by an order, settlement agreement, or plan in effect before November 15, 1990, in any 

area which is a nonattainment area for any air pollutant may be modified after November 15, 1990, in 

any manner unless the modification insures equivalent or greater emission reductions of such air 

pollutant.” Because Rule 420 was adopted into the SIP in 2003, Section 193 does not apply. 
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Rule Evaluation

ICAPCD's Rule 420 includes the following significant provisions: 

• general purpose and applicability; 

• rule requirements; and, 

• definitions used within the rule; 

• exceptions to the rule; and, 

• test methods for determining compliance with the rule. 

The 2006 amendments to Rule 420 change the name of the rule and incorporate permitting requirements for 

confined animal feeding operations consistent with state law. 

We found no deficiencies within the rule. The dust control plan submittal and implementation 

requirements are clear and enforceable. The testable moisture content standard and manure 

management requirements are as stringent as any existing California rule. The rule contains an adequate 

test method for determining moisture content of the livestock corrals according to the rule’s 

requirements. 

Within Section D, the rule provides two exceptions. The first exception is from the 20% minimum 

moisture content standard for 60 days subject to an alternative dust control plan designed to comply with 

the 20% opacity limit in Rule 401 - Opacity. A twenty percent opacity standard is a common RACM 

for PM nonattainment areas. Rule 401 was approved into the SIP on February 3, 1989 (see 54 FR

5448). The second exception is from the 40% moisture content standard during “rainy periods” as 

defined in Rule 101 – Definitions. A “rainy period” is defined as a 24 hour period ending at 4AM 

during which 0.20 to 0.75 inches of rain has fallen. Rule 101 includes this definition and was approved 

into the SIP on November 15, 2007 (see 72 FR 64156.) In sum, we find these exceptions acceptable 

because they are both limited and appropriate to the rule’s intent. 

 In sum, we find that the rule is consistent with Section 110(a)(2) and 172(c)(6) and that the rule 

submittal does not relax the SIP and is consistent with Section 110(l) of the CAA. 

1. Recommendations for Future Revisions

We have no recommendations to suggest at this time. 

Recommendation

Section 110(k) of the CAA contains provisions governing EPA's review of plans and regulations 
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submitted by State of California, air districts, and localities for inclusion in the California State 

Implementation Plan. EPA can propose one of four actions on Rule 420: full approval, conditional 

approval, limited approval/disapproval, or a full disapproval. 

Rule 420 contains no enforceability related deficiencies and the rule does not jeopardize maintenance of 

the NAAQS. In conclusion, EPA proposes an approval of ICAPCD Rule 420 - Beef Feedlots and its 

inclusion into the California State Implementation Plan. 
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Attachments

ICAPCD, Rule 420 - Beef Feedlots, adopted October 10, 2006. Change copy. 

ICAPCD, Rule 420 - Beef Feedlots, adopted October 10, 2006. 

"Issues Relating to VOC (Volatile Organic Compound) Regulation Cutpoints, Deficiencies, and 

Deviations," USEPA, May 28, 1988, cover piece only. 

“Staff Report Amendments to Rule 420 - Beef Feedlots,” Imperial County Air Pollution Control 

District, October 10, 2006.